Microsoft has introduced BitNet b1.58 2B4T, the largest-scale 1-bit AI model to date with 2 billion parameters and the ability to run efficiently on CPUs. It’s openly available under an MIT license. TechCrunch reports: The Microsoft researchers say that BitNet b1.58 2B4T is the first bitnet with 2 billion parameters, “parameters” being largely synonymous with “weights.” Trained on a dataset of 4 trillion tokens — equivalent to about 33 million books, by one estimate — BitNet b1.58 2B4T outperforms traditional models of similar sizes, the researchers claim.
BitNet b1.58 2B4T doesn’t sweep the floor with rival 2 billion-parameter models, to be clear, but it seemingly holds its own. According to the researchers’ testing, the model surpasses Meta’s Llama 3.2 1B, Google’s Gemma 3 1B, and Alibaba’s Qwen 2.5 1.5B on benchmarks including GSM8K (a collection of grade-school-level math problems) and PIQA (which tests physical commonsense reasoning skills). Perhaps more impressively, BitNet b1.58 2B4T is speedier than other models of its size — in some cases, twice the speed — while using a fraction of the memory.
There is a catch, however. Achieving that performance requires using Microsoft’s custom framework, bitnet.cpp, which only works with certain hardware at the moment. Absent from the list of supported chips are GPUs, which dominate the AI infrastructure landscape.
